Disposable active humidifier for the mechanical ventilation of a patient

ABSTRACT

A disposable active humidifier for the mechanical ventilation of a patient, which has the particularity that it comprises a cartridge which forms a humidification chamber which is delimited by an inlet and by an outlet and can be interposed in the ventilation circuit. The cartridge has an interspace which is externally delimited by a heat exchange surface and is internally delimited by a hydrophobic membrane which surrounds the humidification chamber. A humidification fluid, originating from a bottle or bag, can be introduced in the interspace.

RELATED APPLICATIONS

This is a continuation of Ser. No. 10/331,362 filed Dec. 30, 2002,abandoned, which is a continuation of Ser. No. 09/673,594 filed Oct. 18,2000, now U.S. Pat. No. 6,510,848, which is the U.S. national phase ofPCT international application No. PCT/US99/08699 filed Apr. 21, 1999,which claims priority from Italian Application No. MI98 A 000862 filedApr. 22, 1998.

The present invention relates to a disposable active humidifier for themechanical ventilation of a patient.

It is known that the mechanical ventilation of a patient uses dry gaseswhich are humidified before being inspired by the patient. Mostcommercially available systems are based on the principle of making thegas flow directly over the water contained in a heated container.

The conventional solution has a drawback which is constituted by therelatively high volume of the cartridge, which constitutes an additionalbulk; it should be noted that it is very important to reduce bulk, sincein mechanical ventilation, in which the pressure of the ventilatorexpands the lungs of the patient to ventilate him, an extra compressiblespace is certainly a negative factor.

The aim of the invention is indeed to eliminate the drawbacks mentionedabove, which are typical of conventional systems (bacterialcontamination and high compressible volume), by providing a disposableactive humidifier for the mechanical ventilation of a patient which hasa very small bulk and in particular constitutes an integrated segment inthe ventilation circuit and in practice therefore does not increase thevolume of compressible air.

Within the scope of this aim, a particular object of the invention is toprovide a disposable active humidifier which can be prepared in asterile package which can be connected only once to the patient withoutrequiring further handling with the risk of bacterial contamination.

Another object of the present invention is to provide an activehumidifier in which the water remains confined within the cartridge witha continuous supply which in practice forms a closed circuit with noneed for connection to the outside.

Another object of the present invention is to provide a disposableactive humidifier which, by virtue of its particular constructivecharacteristics, is capable of giving the greatest assurances ofreliability and safety in use.

This aim, these objects and others which will become apparenthereinafter are achieved by a disposable active humidifier for themechanical ventilation of a patient, according to the invention,characterized in that it comprises a cartridge which forms ahumidification chamber which is delimited by an inlet and by an outletand can be interposed in a ventilation circuit, said cartridge having aninterspace which is externally delimited by a heat exchange surface andis internally delimited by a hydrophobic membrane which surrounds saidhumidification chamber, a humidification fluid being introducible insaid interspace.

Further characteristics and advantages will become apparent from thedescription of a preferred but not exclusive embodiment, illustratedonly by way of non-limitative example with the aid of the accompanyingdrawings, wherein:

FIG. 1 is a schematic sectional view of a disposable active humidifieraccording to the invention;

FIG. 2 is a schematic view of the active humidifier included in aventilation circuit.

With reference to the above figures, the disposable active humidifierfor the mechanical ventilation of a patient comprises a cartridge,generally designated by the reference numeral 1, which internally formsa humidification chamber 2 which is delimited by an inlet 3 and by anoutlet 4 which are formed on respective caps 5 and 6 which are arrangedmutually opposite at the axial ends of the humidification chamber 2.

The cartridge 1 is externally provided with a heat exchange surface,advantageously constituted by a tubular aluminum casing 10, whichdelimits an interspace 11 formed by a hydrophobic membrane 12 whichdelimits the humidification chamber 2.

Inside the humidification chamber 2 there is a diffuser 20 which ismeant to direct the incoming air stream so that it flows over themembrane 12, so as to facilitate the transfer of humidity through thehydrophobic membrane 12 that delimits the interspace 11, inside whichwater is introduced by means of an inlet 30, to which it is possible toconnect a simple bag or bottle which continuously introduces the waterinto the interspace so that by means of the hydrophobic membrane it ispossible to ensure the required degree of humidity of the air.

It should be added that the diffuser advantageously has protrusions 21shaped like a conical inclined surface, spaced apart from the membrane,which facilitate the conveyance of the air stream against the membrane,which provides a barrier against bacteria, so that the system can besupplied with ordinary distilled water, thus reducing the operatingcosts.

The cartridge 1 can be easily used in a ventilation circuit, designatedschematically by the reference numeral 40 in the drawing, in which thereis a heater 41 which forms the seat for accommodating the externalcasing of the cartridge.

From the above description it is thus evident that the inventionachieves the intended aim and objects, and in particular the fact isstressed that the particular structure that has been used allows toprovide a disposable active humidifier which in practice does notincrease the volume of air present in the ventilation circuit, since itprovides a simple segment which is interposed in the ventilation circuititself.

Furthermore, the new active humidifier is based on an innovativeprinciple which is different from the other systems that arecommercially available, since its humidification principle is based onthe vaporization of water instead of on flowing over water present in aheated container.

The present system uses a humidifier cartridge which is integrated inthe temperature-controlled ventilation circuit and which by vaporizationcharges the dry gases on the inspiratory line of the patient withhumidity.

By virtue of the PVC temperature-controlled circuit in which the heatingresistor is embedded in the external reinforcement spiral, the humidityreleased by the humidifier cartridge does not condense along theinspiratory line but is transferred in full to the patient.

The cartridge of the humidifier (see FIG. 1) is constituted by anexternal body made of metal (aluminum) which acts as interface with theheating element of the humidifier. Inside the cartridge there is ahydrophobic membrane which provides the interface between the liquid andthe vapor phase of the inspiratory line.

The hydrophobic membrane allows the passage of the vapor that forms as aconsequence of the heating of the water contained in the cartridge.

The system can be supplied with ordinary sterile/double-distilled water.

The innovation of the system is that it uses a cartridge which isintegrated in the circuit (see the drawing in the accompanying FIG. 2)and is preassembled to the ventilator with the connections provided.

Differently from flow-over humidification systems, the present systemeliminates the contact of the supply water with the outside environment,avoiding the risk of exogenous contamination of the patient and keepingthe system dry without forming condensate in the ventilation circuit.

The invention thus conceived is susceptible of numerous modificationsand variations, all of which are within the scope of the inventiveconcept.

All the details may furthermore be replaced with other technicallyequivalent elements.

In practice, the materials used, as well as the contingent shapes andthe dimensions, may be any according to the requirements.

1. A disposable active humidifier for humidifying an air stream for the mechanical ventilation of a patient, which comprises: a humidification chamber which is delimited by an inlet and by an outlet and can be interposed in a ventilation circuit for the air stream; a hydrophobic membrane surrounding said humidification chamber for transferring a humidification fluid through said membrane into said humidification chamber; and a diffuser disposed axially inside said humidification chamber, said diffuser being adapted to direct the air stream of the ventilation circuit against said membrane, the diffuser having inclined rings which are spaced apart from said membrane and are adapted to divert the air stream toward said hydrophobic membrane.
 2. A disposable active humidifier according to claim 1, wherein said humidification chamber has a substantially cylindrical shape and forms a segment of said ventilation circuit.
 3. A disposable active humidifier according to claim 1, wherein said outlet and said inlet are formed by respective caps which axially delimit said humidification chamber. 